The purpose of smoke detection within dwellings is to give occupants an early warning of potentially hazardous fires. In the event of a fire, the amount of advance warning time provided to save lives and property is directly related to the sensitivity of the smoke detector that is in service.
Existing smoke detectors in the prior art have not been able to increase the sensitivity substantially without simultaneously increasing the tendency to produce nuisance alarms. In fact, some prior art inventions relate to schemes only for reducing nuisance alarms.
Ionization smoke detectors are prone to nuisance alarms because of their detection of as "smoke", mostly polar molecules including water vapor, moisture, and humidity. Therefore, this technology is viewed as being at its sensitivity limit. Optical light scatter smoke detectors, however, are not so sensitive to water vapor and are therefore not so prone to nuisance alarms as are ionization detectors.
For a light scatter detector to achieve maximum sensitivity, it needs to get as much light as possible into the detection zone. The prior art addressing the sensitivity of light scatter smoke detectors relate to concentrating and focusing (typically using a lens) a single light source on a single spot in the detection zone. They do not consider the use of multiple light sources to increase light intensity. They also do not consider the use of reflective surfaces to concentrate the light. This is probably because they could not determine how to configure the multiple light sources and detector in a way that did not also produce excessive noise light that impairs the detector's ability to distinguish light scattered from particles.
In addition, all smoke detectors rely upon quickly collecting the smoke or other particulate matter from the atmosphere being monitored and into the detection chamber. No prior art found addresses the smoke collection aspect of the smoke detector design. Prior art does not address the use of aerodynamic principles to improve smoke collection.
The technology of the present invention was originally developed to detect the presence of cigarette smoke to enforce smoking restrictions. Cigarette smoke is much less concentrated than is the smoke from a fire, so an ultra-sensitive detector was required. The prior art did not appear to achieve the high level of sensitivity and the resulting improved public safety, partly because of the problem of nuisance alarms.